1. Field of the Invention
The present invention relates to an and apparatus for the absorption-cooling of a fluid, in particular air.
2. Discussion of the Background
Air cooling, commonly known as air conditioning, is achieved by two different systems.
A first system, widely used for air conditioning in buildings and vehicles, uses compressors operating with chlorofluorocarbons and driven by electric motors or vehicle engines.
A second system, known as an absorption system, operating normally with saline solutions, is applied in practice only to very large buildings because although it consumes very little electric power it requires large cooling towers to disperse the heat produced.
Traditional air conditioners of the compressor type consume considerable power, this being very important when used in vehicles. In addition, air conditioners of this type are very dependent in operation on the engine r.p.m. when installed in motor vehicles.
It should also be noted that the use of chlorofluorocarbons constitutes a serious source of ecological damage, as is now well known throughout the world.
Air conditioning machines of absorption type have many undoubted advantages over air conditioners of compressor type, both in terms of electrical power consumption, which is very low, and in ecological terms as the saline solutions generally used cause no damage if lost to the environment external to the apparatus.
However, absorption air conditioners produce a very large heat quantity to be dispersed, this quantity being double that of compressor air conditioners of equal capacity. This heat has to be at least partly dispersed from an aqueous saline solution, generally of lithium bromide, having a temperature of about 42.degree. C., to produce very cold water at about 4.degree. C., usable for cooling the air to be conditioned. This temperature of 42.degree. C., which is very close to the temperature reached during the summer months in many countries, including those of temperate climate, is often less than the temperature reached in hot or equatorial countries. Thus in no way can the external air be used as a cooling medium, and in fact currently known absorption air conditioners comprise cooling water circuits for the saline solution, this water then being cooled in evaporative cooling towers, making it impossible to apply the system to vehicles or small users.
As is well known to the expert of the art, the saline solution temperature of 42.degree. C. is strictly related to the vapor pressure of the very cold water and to the solution concentration. An increase in this temperature could only be achieved by increasing the salt concentration in the solution, but in practice this is not possible under normal working conditions because the salt concentration in the water is already very close to the crystallization curve, and the formation of crystals within the solution circulation circuits is obviously to be totally avoided.